Method for manufacturing circuit devices

Abstract

Semiconductor devices wherein a flexible sheet with a conductive pattern was employed as a supporting substrate, a semiconductor element was mounted thereon, and the ensemble was molded have been developed. In this case, problems occur in that a multilayer wiring structure cannot be formed and warping of the insulating resin sheet in the manufacturing process is prominent. In order to solve these problems, a laminated plate 10 in which a thin, first conductive film 11 and a thick, second conductive film 12 have been laminated via a third conductive film 13 is used. In a step for forming a first conductive wiring layer 11 A by etching the first conductive film 11 , etching depth can be controlled by a stop of etching at the third conductive film 13 . Accordingly, forming the first conductive film 11 thin makes it possible to form the first conductive wiring layer 11 A into a fine pattern. In addition, since a second conductive wiring layer 14 A is formed via a first insulating layer 15 , multilayer wiring can be realized.

What is claimed is:  
     
         1 . A method for manufacturing circuit devices comprising: 
 preparing a laminated plate by laminating a first conductive film and a second conductive film via a third conductive film;    forming a first conductive wiring layer by etching said first conductive film into a desirable pattern;    selectively removing said third conductive film by use of said first conductive wiring layer as a mask;    laminating an insulating sheet where a first insulating layer has been fitted to a fourth conductive film so that said first insulating layer covers front-surface portions of the second conductive film exposed by removing said third conductive film, said first conductive wiring layer, and end faces of the third conductive film;    forming a second conductive wiring layer by etching said fourth conductive film into a desirable pattern;    forming multilayer connecting means and thus electrically connecting said first conductive wiring layer with said second conductive wiring layer;    covering said second conductive wiring layer with a second insulating layer;    forming exposed portions by selectively exposing said second conductive wiring layer by partially removing said second insulating layer;    fixedly fitting semiconductor elements onto said second insulating layer to electrically connect said semiconductor elements with said second conductive wiring layer;    covering said semiconductor elements with a sealing resin layer;    removing said second conductive film to expose said third conductive film on the rear surface.    
     
     
         2 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said conductive wiring layer is formed by performing etching up to said third conductive film.    
     
     
         3 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 a solution to etch said first conductive film is used.    
     
     
         4 . The method for manufacturing circuit devices as set forth in  claim 3 , wherein 
 as said solution for performing said etching, a solution containing ferric chloride or cupric chloride is used.    
     
     
         5 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said third conductive film is removed by electrolytic peeling.    
     
     
         6 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said third conductive film is removed by etching by use of a solution to etch said third conductive film.    
     
     
         7 . The method for manufacturing circuit devices as set forth in  claim 6 , wherein 
 said solution is an iodine-based solution.    
     
     
         8 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said second conductive film is entirely etched.    
     
     
         9 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said second conductive film is formed thicker than said first conductive film.    
     
     
         10 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said insulating layer is a thermoplastic resin, a thermosetting resin, or a photosensitive resin.    
     
     
         11 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said first conductive film and said second conductive film are metals made of copper as a main material, and said third conductive film is a metal made of silver as a main material.    
     
     
         12 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said laminated plate is manufactured by laminating said third conductive film and said first conductive film by electroplating while using said second conductive film as a base.    
     
     
         13 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said laminated plate is formed by rolling.    
     
     
         14 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said exposed and plated, first conductive film part and electronic components excluding semiconductor elements are electrically connected.    
     
     
         15 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said insulating sheet is formed by vacuum press or vacuum lamination.    
     
     
         16 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said insulating layer is partially removed by laser processing.    
     
     
         17 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 said insulating layer is partially removed by a lithographic method.    
     
     
         18 . The method for manufacturing circuit devices as set forth in  claim 1 , wherein 
 by electrolytic plating using said second conductive layer as an electrode, a metal mainly of copper is built up in through holes formed by partially removing said first insulating layer, and said first conductive wiring layer and said second conductive wiring layer are thus connected.